If this is the sense of semantic meaning that's relevant, it's not clear to me why there's anything special about DNA. Doesn't a particular collection of rocks and branches mean, "This is a stream bed," in the same sense?
Valid point. All nature is equally a kind of speech. DNA’s uniqueness is not in being speech but in being so “talkative,” as compared to a bunch of rocks. And the intelligibility of nature’s speech points to an Intelligence as the source of nature’s speech. To echo Subduction Zone, communication exists only in and between minds.
Not, it distinctly is not. Language in general has distinct patterns to such an extent that a language for communication can be distinguished just through the frequency of sounds (or equivalent to that language). This is how we can tell dolphins use a complex language to communicate and have names for each other, even though we can't "speak dolphin". This is also how we can tell the background electromagnetic static in the universe isn't a language, since it has no such patterns. Pattern distinctions are one of the things the brains of our species are exceptionally good at, such that if there were "speech" in all of nature, we would have noticed it.
Depending upon what said "rocks" consist of, they could engage in more chemical reactions than DNA does.
If it were intelligible, people would either be constantly working to decode it, or would have by now. Nature in general doesn't have language like patterns.
Of which the universe or "nature" either doesn't have, or has no interest or capability of utilizing it to communicate with us.
DNA itself is not the other mind, just as speech itself is not a mind but a product and expression of mind. If anything has been learned from DNA, then the communication of ideas that we ourselves did not originate has taken place. And as intelligence is the indispensable condition of originating and reproducing ideas, this communication too is between Mind and mind.
Language is the communication of thought via signs or symbols, and nature’s speech is full of patterns and intelligible, and we are constantly decoding it, even if we are not consciously aware of the process. For example, patterns of light and dark and color are the “letters” of the language of vision. We “read” these patterns and discern their meaning and thereby come to know the external world around us. The fact that the world is thus knowable and meaningful, that we can form accurate conceptions of the world around us, constitutes the world’s rationality or intelligibility. The world around us is, then, a thought world, otherwise we could not think or conceive it in our own minds. Thus we constantly reproduce the vision of the external world in our own minds through decoding intelligible patterns, and still more obscurely through a process of nervous impulses that look nothing at all like the external world. In the latter case, we have an analogy with decoding a radio signal that conveys intelligible information concerning the external world. For intelligible information to result, the signal must first be the purposeful product of intelligence, otherwise the signal will produce only unintelligible white noise. In the same way, nature and its speech are intelligible to us because they are the purposeful product of intelligence. And since our minds do not originate this intelligible content of the world, we refer it to another Intelligence.
